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The Balance of Expression of Dihydroflavonol 4-reductase and Flavonol Synthase Regulates Flavonoid Biosynthesis and Red Foliage Coloration in Crabapples.

Tian J, Han ZY, Zhang J, Hu Y, Song T, Yao Y - Sci Rep (2015)

Bottom Line: Levels of anthocyanins and the transcript abundances of the anthocyanin biosynthetic gene, dihydroflavonol 4-reductase (McDFR) and the flavonol biosynthetic gene, flavonol synthase (McFLS), were assessed during the leaf development in two crabapple cultivars, 'Royalty' and 'Flame'.The concentrations of anthocyanins and flavonols correlated with leaf color and we propose that the expression of McDFR and McFLS influences their accumulation.These results suggest that the relative activities of McDFR and McFLS are important determinants of the red color of crabapple leaves, via the regulation of the metabolic fate of substrates that these enzymes have in common.

View Article: PubMed Central - PubMed

Affiliation: 1] Department of Plant Science and Technology, Beijing University of Agriculture, Beijing, China [2] Key Laboratory of New Technology in Agricultural Application of Beijing, Beijing University of Agriculture, Beijing, China.

ABSTRACT
Red leaf color is an attractive trait of Malus families, including crabapple (Malus spp.); however, little is known about the molecular mechanisms that regulate the coloration. Dihydroflavonols are intermediates in the production of both colored anthocyanins and colorless flavonols, and this current study focused on the gene expression balance involved in the relative accumulation of these compounds in crabapple leaves. Levels of anthocyanins and the transcript abundances of the anthocyanin biosynthetic gene, dihydroflavonol 4-reductase (McDFR) and the flavonol biosynthetic gene, flavonol synthase (McFLS), were assessed during the leaf development in two crabapple cultivars, 'Royalty' and 'Flame'. The concentrations of anthocyanins and flavonols correlated with leaf color and we propose that the expression of McDFR and McFLS influences their accumulation. Further studies showed that overexpression of McDFR, or silencing of McFLS, increased anthocyanin production, resulting in red-leaf and red fruit peel phenotypes. Conversely, elevated flavonol production and green phenotypes in crabapple leaves and apple peel were observed when McFLS was overexpressed or McDFR was silenced. These results suggest that the relative activities of McDFR and McFLS are important determinants of the red color of crabapple leaves, via the regulation of the metabolic fate of substrates that these enzymes have in common.

No MeSH data available.


Related in: MedlinePlus

Transient expression of McFLS in apple fruit.McFLS expression was suppressed in apple fruit using the vector pTRV2- McFLS, or overexpressed using the vector pBI121- McFLS. Apple fruit injected with the empty TRV and pBI121 vectors and infiltration buffer were used as controls. (A) Phenotype of McFLS silenced or McFLS overexpressing apple peels. (B) Anthocyanin and flavonol contents at the infiltration sites of apple peels in μg/g fresh weight (FW). (C) Relative expression levels were determined using qRT-PCR around the infiltration sites. Error bars indicate the standard error of the mean ± SE of three replicate measurements. Different letters above the bars indicate significantly different values (P < 0.05) calculated using one-way analysis of variance (ANOVA) followed by a Duncan’s multiple range test.
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f7: Transient expression of McFLS in apple fruit.McFLS expression was suppressed in apple fruit using the vector pTRV2- McFLS, or overexpressed using the vector pBI121- McFLS. Apple fruit injected with the empty TRV and pBI121 vectors and infiltration buffer were used as controls. (A) Phenotype of McFLS silenced or McFLS overexpressing apple peels. (B) Anthocyanin and flavonol contents at the infiltration sites of apple peels in μg/g fresh weight (FW). (C) Relative expression levels were determined using qRT-PCR around the infiltration sites. Error bars indicate the standard error of the mean ± SE of three replicate measurements. Different letters above the bars indicate significantly different values (P < 0.05) calculated using one-way analysis of variance (ANOVA) followed by a Duncan’s multiple range test.

Mentions: To further characterize the roles of McDFR and McFLS, we infected apple (Malus × domestica ‘Fuji’) fruits with transgenic Agrobacterium harboring TRV-McDFR, TRV-McFLS, pBI121-McDFR or pBI121-McFLS constructs (Figs 6 and 7). A large increase in anthocyanin accumulation was observed at the sites of TRV-McFLS and pBI121-McDFR over-expression, while the areas of TRV-McDFR and pBI121-McFLS over-expression showed a yellow or white coloration (Figs 6A and 7A). HPLC quantification of the anthocyanin and flavonol content of the infected areas confirmed that the variation in flavonoid content correlated with the observed variation in fruit color (Figs 6B and 7B). Transcript expression analysis of the transiently expressing tissues further revealed that the up-regulation of McDFR expression, or the down-regulation of McFLS expression, was accompanied by a proportional increase in the expression levels of McDFR as well as some of the genes involved in anthocyanin biosynthesis (McCHS, McCHI, McF3H, McF3′H, McDFR, McANS and McUFGT), and a decrease in the expression levels of McFLS. Importantly, up-regulation of McFLS expression or down-regulation of McDFR expression resulted in fading leaf color and decrease McDFR gene expression (Figs 6C and 7C). Finally, we compared the relationship between the expression of McDFR and the content of anthocyanins, and the results were consistent with the red color formation in leaves and fruit; as well as between the levels of McFLS and the content of flavonols (Figs 5 and 6).


The Balance of Expression of Dihydroflavonol 4-reductase and Flavonol Synthase Regulates Flavonoid Biosynthesis and Red Foliage Coloration in Crabapples.

Tian J, Han ZY, Zhang J, Hu Y, Song T, Yao Y - Sci Rep (2015)

Transient expression of McFLS in apple fruit.McFLS expression was suppressed in apple fruit using the vector pTRV2- McFLS, or overexpressed using the vector pBI121- McFLS. Apple fruit injected with the empty TRV and pBI121 vectors and infiltration buffer were used as controls. (A) Phenotype of McFLS silenced or McFLS overexpressing apple peels. (B) Anthocyanin and flavonol contents at the infiltration sites of apple peels in μg/g fresh weight (FW). (C) Relative expression levels were determined using qRT-PCR around the infiltration sites. Error bars indicate the standard error of the mean ± SE of three replicate measurements. Different letters above the bars indicate significantly different values (P < 0.05) calculated using one-way analysis of variance (ANOVA) followed by a Duncan’s multiple range test.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4507444&req=5

f7: Transient expression of McFLS in apple fruit.McFLS expression was suppressed in apple fruit using the vector pTRV2- McFLS, or overexpressed using the vector pBI121- McFLS. Apple fruit injected with the empty TRV and pBI121 vectors and infiltration buffer were used as controls. (A) Phenotype of McFLS silenced or McFLS overexpressing apple peels. (B) Anthocyanin and flavonol contents at the infiltration sites of apple peels in μg/g fresh weight (FW). (C) Relative expression levels were determined using qRT-PCR around the infiltration sites. Error bars indicate the standard error of the mean ± SE of three replicate measurements. Different letters above the bars indicate significantly different values (P < 0.05) calculated using one-way analysis of variance (ANOVA) followed by a Duncan’s multiple range test.
Mentions: To further characterize the roles of McDFR and McFLS, we infected apple (Malus × domestica ‘Fuji’) fruits with transgenic Agrobacterium harboring TRV-McDFR, TRV-McFLS, pBI121-McDFR or pBI121-McFLS constructs (Figs 6 and 7). A large increase in anthocyanin accumulation was observed at the sites of TRV-McFLS and pBI121-McDFR over-expression, while the areas of TRV-McDFR and pBI121-McFLS over-expression showed a yellow or white coloration (Figs 6A and 7A). HPLC quantification of the anthocyanin and flavonol content of the infected areas confirmed that the variation in flavonoid content correlated with the observed variation in fruit color (Figs 6B and 7B). Transcript expression analysis of the transiently expressing tissues further revealed that the up-regulation of McDFR expression, or the down-regulation of McFLS expression, was accompanied by a proportional increase in the expression levels of McDFR as well as some of the genes involved in anthocyanin biosynthesis (McCHS, McCHI, McF3H, McF3′H, McDFR, McANS and McUFGT), and a decrease in the expression levels of McFLS. Importantly, up-regulation of McFLS expression or down-regulation of McDFR expression resulted in fading leaf color and decrease McDFR gene expression (Figs 6C and 7C). Finally, we compared the relationship between the expression of McDFR and the content of anthocyanins, and the results were consistent with the red color formation in leaves and fruit; as well as between the levels of McFLS and the content of flavonols (Figs 5 and 6).

Bottom Line: Levels of anthocyanins and the transcript abundances of the anthocyanin biosynthetic gene, dihydroflavonol 4-reductase (McDFR) and the flavonol biosynthetic gene, flavonol synthase (McFLS), were assessed during the leaf development in two crabapple cultivars, 'Royalty' and 'Flame'.The concentrations of anthocyanins and flavonols correlated with leaf color and we propose that the expression of McDFR and McFLS influences their accumulation.These results suggest that the relative activities of McDFR and McFLS are important determinants of the red color of crabapple leaves, via the regulation of the metabolic fate of substrates that these enzymes have in common.

View Article: PubMed Central - PubMed

Affiliation: 1] Department of Plant Science and Technology, Beijing University of Agriculture, Beijing, China [2] Key Laboratory of New Technology in Agricultural Application of Beijing, Beijing University of Agriculture, Beijing, China.

ABSTRACT
Red leaf color is an attractive trait of Malus families, including crabapple (Malus spp.); however, little is known about the molecular mechanisms that regulate the coloration. Dihydroflavonols are intermediates in the production of both colored anthocyanins and colorless flavonols, and this current study focused on the gene expression balance involved in the relative accumulation of these compounds in crabapple leaves. Levels of anthocyanins and the transcript abundances of the anthocyanin biosynthetic gene, dihydroflavonol 4-reductase (McDFR) and the flavonol biosynthetic gene, flavonol synthase (McFLS), were assessed during the leaf development in two crabapple cultivars, 'Royalty' and 'Flame'. The concentrations of anthocyanins and flavonols correlated with leaf color and we propose that the expression of McDFR and McFLS influences their accumulation. Further studies showed that overexpression of McDFR, or silencing of McFLS, increased anthocyanin production, resulting in red-leaf and red fruit peel phenotypes. Conversely, elevated flavonol production and green phenotypes in crabapple leaves and apple peel were observed when McFLS was overexpressed or McDFR was silenced. These results suggest that the relative activities of McDFR and McFLS are important determinants of the red color of crabapple leaves, via the regulation of the metabolic fate of substrates that these enzymes have in common.

No MeSH data available.


Related in: MedlinePlus